Abstract. The Middle Eocene Climatic Optimum (MECO), a ∼500 kyr episode of
global warming that initiated at ∼ 40.5 Ma, is postulated to be
driven by a net increase in volcanic carbon input, but a direct source has not
been identified. Here we show, based on new and previously published
radiometric ages of volcanic rocks, that the interval spanning the MECO
corresponds to a massive increase in continental arc volcanism in Iran and
Azerbaijan. Ages of Eocene igneous rocks in all volcanic provinces of Iran
cluster around 40 Ma, very close to the peak warming phase of the
MECO. Based on the spatial extent and volume of the volcanic rocks as well as
the carbonaceous lithology in which they are emplaced, we estimate the total
amount of CO2 that could have been released at this time corresponds
to between 1052 and 12 565 Pg carbon. This is compatible with the
estimated carbon release during the MECO. Although the uncertainty in both
individual ages, and the spread in the compilation of ages, is larger than the
duration of the MECO, a flare-up in Neotethys subduction zone volcanism
represents a plausible excess carbon source responsible for MECO warming.
Exploring a link between the Middle Eocene Climatic Optimum and Neotethys continental arc flare-up
